Suction filter



June 6, 1950 J. c. F. c. RICHTER SUCTION FILTER I Filed Nov. 26, 1945 Jm enfor:

Patented June 6, 1950 SUCTION FILTER Johan Christoiier Fredrik Carl Richter, Karlstad, Sweden, assignor to Aktiebolaget Kamyr, Karlstad, Sweden, a company 01' Sweden Application November 26, 1945, Serial No. 630,864 In Sweden June 19, 1941 Section 1, Public Law 690, August 8, 1946 Patent expires June 19, 1961 5 Claims.

The present invention relates to an improvement in suction filters of the kind which are used for extracting fibres or the like in the form of a web of material from a pulp mixture and, optionally, for simultaneously washing such web of material by spraying water on the same. Such filters comprise a tank which contains the pulp mixture, and a rotary sieve drum which is partially immersed in the pulp mixture in said tank, said sieve drum being provided with a perforated sieve shell which is closed at its ends by means of drum heads, so that the interior of the drum forms a closed suction chamber, which is maintained under vacuumby means of a suction and water discharge pipe, which'is connected to the drum. The liquid head of the pulp mixture in the tank and the suction or vacuum maintained in the interior of the drum cause the water in the pulp mixture to fiow through the perforations in the sieve shell into the interior of the drum. while the fibres in the pulp mixture deposit on said sieve shell and form thereon a cake or web which is raised out of the pulp mixture while the drum rotates. In order to enable or facilitate the removal of the said web of material from the sieve shell there is provided in the interior of the drum a shield, which is stationary relatively to the drum and may be adjustable relatively to the same, and which serves to shield off a portion of the inner surface of the sieve shell from the suction in the drum at that zone of the sieve shell where the web of material is removed from the outer face of the drum.

It is an object of the present invention to provide a construction of a suction filter of the type above referred to, which avoids the use of a stationary shaft for supporting the abovementioned shield which serves to shield off a portion of the inner surface of the sieve shell from the suction in the drum, and thus to avoid the necessity of either using large-size bearings, and stufiing boxes for such bearings,'for rotatably supporting the drum on such stationary shaft within the tank, or using large hollow trunnions surrounding such stationary shaft and large bearings for rotatably supporting the drum in the tank.

It is an important object of the present invention, therefore, to provide a construction which renders it possible to support the abovementioned shield from a portion of the wall of the tank which constitutes a stationary head member of the drum, so that the said shield may be supported from a point eccentric to the axis of the drum, and thus to provide a construction which renders it possible to rotatably support the sieve drum by means of an ordinary solid shaft connected to and rotating with the drum, and which need only be dimensioned with respect to the weight of the drum and the torque required for rotating the drum, and which may, therefore, have minimum dimensions. This improvement renders it possible to journal the said shaft in bearings which may be located outside the tank of the filter, and which are thus well protected from the influence *of the water in the tank, so that such bearings may be constructed as ball or roller bearings of standard size.

It is a further object of the invention to provide a construction which renders it possible to locate the discharge pipe from the drum in the abovementioned stationary head member, in a position eccentric to the axis of the drum, whereby said discharge pipe will not interfere with the shaft and bearings of the drum, and thus to avoid the use as a discharge means of a large tubular trunnion of the drum which necessitates a large bearing and a large and expensive seal between such rotary trunnion and a fixed discharge pipe.

A further object of the invention is to provide a construction wherein the abovementioned stationary head member supporting the shield and to which the discharge pipe is connected, may be made of a small size, so that the seal or stuffing box between said stationary head member and the adjacent rotary part of the drum may be made of a minimum size, so that it can be constructed in a simple and yet efficient and reliable manner, and the invention also provides other advantages which will be apparent from the following description of two constructional forms of filters according to the invention, which are shown by way of example and somewhat diagrammatically in the accompanying drawing.

Fig. 1 shows one constructional form in axial section on the line I -I in Fig. 3, and Fig. 2 shows an axial section of the same filter on the line 11-11 in Fig. 3, while Fig. 3 shows a cross section of the filter partly on the line IIIIII in Fig. l, and partly on the line IIIa--III in Fig. 2. Fig. 4 shows an axial section of a second constructional form. Fig. 5 shows a detail view of a member attached to the tank of the filter, partly in end view as seen from the right in Fig. 1, and partly in cross section on the line V--V in Fig. 1,

Referring to Figs. 1 to 3 inclusive, i denotes a tank containing the pulp mixture in which the rotary filter drum 2 is partially immersed, the cylindrical portion of said drum consisting of a sieve shell 3 or envelop perforated in a suitable manner. In the instance illustrated in Figs. 1 to 3 inclusive, the left end of sieve shell 3 is closed by a drum head 4 and is supported by a suitable spider 4a which may be formed integrally with the drum.head, as viewed in Fig. 1, said drum head 4 being secured to the shaft 5 which near this end of the drum passes through a stuffing box 6 in the wall of the tank I and is supported in a, bearing 1 provided outside the said wall. Secured to the end of the shaft projecting beyond the said bearing 1 is a toothed gear wheel 8 or the like by means of which rotational movement is transmitted to the drum from any suitable driving means not illustrated in the drawing.

The other head 9 of the sieve drum at the right-hand end thereof, is secured to the sieve shell 3 and is provided with an opening 29 which is concentric to the axis of rotation of the sieve drum and which has a smaller diameter than the outside diameter of the sieve drum, as will be seen from the drawing. The edge or rim of the said opening 29 cooperates with the adjacent wall of the tank I against which it is sealed by suitable sealing means. In the instance illustrated. a cylindrical member 10 which is concentric to the axis of rotation of the drum, is attached to the wall of the tank I by being inserted through a corresponding aperture in said wall to which it may be secured by any suitable means well known in the art, such as bolts screwed into said wall through holes 4| in an outer flange 42 on said member Ill, see Fig. 5. Said member I!) extends from the wall of the tank into the drum through the abovementioned opening 29 in the head 9 thereof, the rim of the said opening 29 being sealed against the exterior surface of the member Ill by means of a stulfing box II. In the instance illustrated the space within the member II] is closed at the inner end thereof by a wall l2 so that the member ID and said Wall form a box-like recess 43 in the wall of the tank, the wall 12 constituting the stationary head member of the drum. The wall I2 is provided with a stuffing box I3 through which the shaft 5 of the sieve drum passes, and there is also provided in said wall l2 an aperture l4 which forms the mouth of the suction and water discharge pipe IS. The end of the shaft 5 projecting through the wall I2 is supported by a bearing l6 which in this case is supported on the said pipe H) which is made integral with the member I.

Mounted on the portion of the member H] which projects into the interior of the sieve drum 2, is a support I! for a shield or bafile plate l8 which cooperates with the interior surface of the sieve drum at that zone thereof where the web of material is removed from the outer face of the sieve shell. as for instance by the a d of a discharge roll l9, Fig. 3. In the instance i1- lustrated in Figs. 1 to 3 inclusive, the sieve shell is not provided with cells along its interior surface, and therefore, the shield l8 which ma be provided with a, suitable packing, not shown in the drawing, along its edges, extends over the entire width of the sieve shell.

A filter constructed as above described may easily be arranged as a washing filter. In this case the filter is provided in the manner illustrated in Figs. 2 and 3 with a suitable number of hoppers in the interior of the sieve drum for receiving the washing water used, two such hoppers 20 and 2| being shown in the drawing, said hoppers being secured to and carried by the memwith the said member l0, and to which discharge pipes 24 and 25, respectively, are connected in any suitable manner, such as by said pipes being screw-threaded into holes in the portion of the wall l2 intermediate said compartments 22 and 23, respectively, and th recess 43. The washing water is supplied by means of spray pipes 28 and 21 provided outside the sieve drum, and the washing may suitably be carried out by spraying fresh water through the spray pipe 21 on to the web of material above the hopper 2|, after which the water discharged through the discharge pipe 25 is drawn through the pipe 44 and is forced by the pump 45 through the pipe 46 to the spray pipe 26 and sprayed through the latter over the web of material above the hopper 20. The water discharged from said hopper through the discharge pipe 24 to the pipe 41 may be used as a weak lye.

The constructional form illustrated in Fig. 4 is substantially similar to that above described in connection with Figs. 1 to 3 inclusive, and similar reference numerals are used to denote corresponding parts. In the case of Fig. 4, however, the sieve drum 2 is provided with cells 3| located along the inner circumference of the sieve shell 3 in the axial direction of the drum, said cells being separated from one another in a wellknown manner by partitions extending in the axial direction, and from the interior of the drum by an inner shell or bottom 32 in which there is provided an opening 33 for each cell, said opening being located close to the head 9 of the drum which is provided with an opening 29 concentric to the axis of rotation, and a stationary portion of which is formed by a portion of the wall of v head 9 of the drum, it is possible to provide a spider 34 for the support of the. drum adj cent said head 9, and therefore, it is not necessary to provide the drum with a through shaft, as in place thereof the drum may be provided with shafts 35 and 36 secured to the head 4 and to the spider 34, respectively. At the zone where the web of material is removed from the outside of the sieve shell, the required number of cells are shut off from-the suction in the interior of the drum by means of a shield or baffle plate 31, the support 38 of which may also in this case be secured to the member ID, in which the suction and water discharge pipe [5 is also provided in the same manner as in the construction above described with reference to Figs. 1 to 3 inclusive. Also in this case it is of course possible to provide water collecting hoppers or compartments below the openings 33 in the bottoms of a, suitable number bf cells 3| for receiving washing water from such cells in a manner corresponding to that above described in connection with Figs. 1 to 3 inclusive.

It will be readily understood that in the two constructional forms above described the wall l2 need not be located at the inner end of the member In, as the said Wall l2 may be located, for instance, in the same plane as the wall of the tank or even outside the wall of the tank, in such manner that only a cylindrical flange projects into the opening 29 in the head 9, or alternatively, the head 9 may be provided at the rim of the opening 29 with a flange which is directed towards the wall of the tank and sealed against the same. The construction above described and illustrated in the drawing provides a, more rigid structure, however, and a firmer support of the members in the interior of the sieve drum, and in addition, the shaft of the drum becomes shorter, and the bearing for the shaft at this end of the drum does not need to project far outside the tank.

I claim:

1. In a suction filter of the character described,

.the combination of a, tank serving,to receive a head member, said wall structure including a portion forming a stationary closure member for said opening in said drum head member and cooperating with said drum head member and said closing means at the opposite end of said sieve shell to form a closed suction chamber in sa d s'ieve drum,.,a suction and water discharge pine connected to the drum so as to maintain suction in the interior thereof and remove water therefrom, sealing means between said drum head member and said stationary closure member, a stationary shield positioned within said sieve shell and cooperating with a portion of the inner surface thereof at" a zone from which the material is removed from the outer surface of said sieve shell so as to shield 01! said portion of the sieve shell from the suction within the drum,

means on said stationary closure member for supporting said stationary shield, said shaft eans extending through said stationary closure member to the outer side thereof, and a bearing for said shaft pivot located on the outer side of sa d stationary closure member.

2. In a suction filter of the character described, the combination of a tank serving to receive a pulp mixture, a sieve drum comprising a rotatable perforated sieve shell mounted so as to be partially immersed in the pulp mixture in said tank, means including rotatable shaft means for rotatably supporting said sieve shell, a drum head member secured to said sieve shell at one end thereof so as to rotate therewith and having a central opening, means closing the opposite end of said sieve shell, said tank having a wall structure disposed adjacent said drum head member, said wall structure including a cylindrical member concentric with the axis of rotation of said sieve shell, sealing means between said drum head member and said cylindrical member, and a wall member closing the space within said cylindrical member and forming a stationary closure member for said opening in said drum head member, a suction and water discharge pipe connected to the'drum soas to maintain suction inthe interior thereof and remove water therefrom, a stationary shield positioned within said "sieve shell and cooperating with a portion of the inner terial is removed from the'outer surface of said surface thereof at a zone from which the masieve shell so as to shield off said portion of the sieve shell from the suction within the drum, means on said cylindrical member for supporting said stationary shield, said shaft means extending through said wall member to the outer side thereof, and a bearing for said shaft means located on the outer side of said wall member,

3. In a suction filter of the character described, the combination of a tank serving to receive a pulp mixture; a sieve drum comprising a rotatable perforated sieve shell mounted so as to be partially immersed in the pulp mixture in said tank, means including rotatable shaft means for rotatably supporting said sieve shell, a drum head member secured to said sieve shell at one end thereof so as to rotate therewith and having a central opening, means closing the opposite end of said sieve shell, said tank having a wall structure disposed adjacent said drum head member, said wall structure including cylindrical member concentric with the axis of rotation of said sieve shell and projecting through the opening in said drum head member into the interior of the drum, sealing means between said drum head member and said cylindrical member, and a wall member closing the space within said cylindrical member and forming a'stationary closure member for said opening in said drum head member,

a suction and water discharge pipe connected to the drum so as to maintain suction in the interior thereof and remove water therefrom, a stationary shield positioned within said sieve shell and cooperating with'a portion of the inner surface thereof at a zone from which the material is removed from the outer surface of said sieve shell so as to shield off said portion of the sieve shell from the suction within the drum, means on said cylindrical member for supporting said stationary shield, said shaft means extending through said wall member to the outer side thereof, and a bearing for said shaft means located on the outer side of said wall member.

I 4. A suction filter as defined in claim 1, further comprising hoppers in the interior of the drum for receiving spray water, said hoppers being attached to and supported by said stationary closure member, and means for dischargin water from said hoppers. v

5. A suction filter as defined in claim 1, where- .in the suction and water discharge pipe is connected to the interior of the drum through the stationary closure member.

JOHAN CHRISTOFFER FREDRIK CARL RICHTER.

REFERENCES CITED The following references are of record in the file of this patent:

Evans June 9, 1942 

